Archive for the ‘Nanoscience’ Category

Researchers at Lanzhou University, China, have designed a nanocomposite to effectively remove cadmium ions from human blood.

Previous materials designed for this purpose have either had good selectivity, high saturation magnetisation or good water dispersibility, but the new material has all three properties. And, the composite is highly supermagnetic, making subsequent removal of the nanoparticles easier.

Removing cadmium (which is produced during industrial processes) from the blood is important because they bind to proteins in the body, affecting their functions.

The nanocomposite consists of four components; The first is magnetic iron oxide nanoparticles, chosen for their low toxicity. They are coated with polyethylenimine to increase the amino groups on the particles’ surface to bind Cd2+, but also to lower nanoparticle uptake by red blood cells, maximising the circulation time of the composites in the blood. Polyethylene glycol is grafted onto this as an anchor for negatively charged 2,2’-phenylazanediyl, which counteracts the hydrophobic and electrostatic interactions between the nanoparticles and plasma proteins or white blood cells.

Chinese scientists have used graphene sheets to wrap silicon nanoparticles to make nanocomposites which resemble bath lilies.

Zi-Feng Ma and co-workers, from Shanghai Jiao Tong University, have assessed the performance of the novel bath lily-like graphene sheet-wrapped silicon (GS-Si) nanocomposites as anode materials for Li-ion batteries. They showed that the GS-Si nanocomposites exhibit a high reversible capacity of 1525mAh g-1 and superior cycling stability. Conventional graphite anodes display a theoretical specific capacity of only 372 mAh g-1, making it a weak candidate for anodes of Li-ion batteries.

The GS-Si nanocomposites were synthesised using a spray-drying technique which requires “no surfactant, no filtration or washing processes and no high vacuum conditions.” The authors believe that the procedure is safe and environmentally friendly and can be scaled up for the mass production of graphene-based composite materials.

The obtained GS-Si composite possesses an open nano/micro-structure, in which nanosized Si particles are uniformly dispersed and wrapped in the graphene sheet (GS) matrix. “The GS not only constitutes a good conducting network, but also provides enough void spaces to accommodate the volume change of Si and prevent the aggregation of nano-Si particles during cycling, ” explains Ma et al.

Find out more about graphene sheet-wrapped nanocomposites by downloading the full article for free until December 2012.

Scientists from China have synthesized novel polystyrene (PS) fibrous mats consisting of highly porous fibers which show much higher oil absorption capacities compared to the commercially available polypropylene fibers.

The authors say that such regulation of micro- and nanostructures of the PS fibers will widen the range of their applications in self-cleaning materials, ultra-high sensitivity sensors, tissue engineering and ion exchange materials.